LTE (Long Term Evolution) is the evolution of 3G (3rd Generation), it improves and enhances the air access technology of 3G, using OFDM (Orthogonal Frequency Division Multiplexing) and MIMO (Multiple Input Multiple Output) as the only standard of the evolution of wireless network. Wherein, in LTE system and previous wireless communication system, a cell only has a carrier, as shown in FIG. 1, and the max bandwidth is 20 MHz; In 20 MHz spectrum bandwidth, LTE can provide the peak rate of downlink is 100 Mbit/s and the peak rate of uplink is 50 Mbit/s, ameliorating the performance of cell edge users, improving cell capability and reducing system delay. In LTE system, UE (User Equipment) working in one carrier at the same time, while one LTE cell having only one carrier, each LTE cell identified by only one number in network. UE can receives and transmits data only in one cell at the same time, and this cell is called “serving cell” for UE.
In addition, with the rapid growth of the number of mobile user, traffic of mobile user increases exponentially. To satisfy the continuously increased traffic requirements of mobile user, it is need to provide more larger bandwidth for traffic transmission of mobile user and higher peak rate which applications requires. In LTE-A (LTE-Advanced) system, the peak rate has a huge boost than LTE. It requires 1 Gbps for downlink and 500 Mbps for uplink, while, if only using a carrier with the max bandwidth of 20 MHz, it can't reach the requirements of the peak rate. So, LTE-A needs to expand the bandwidth the terminal user used, then introduced CA (Carrier Aggregation) technology. There are multiple cells in which UE receives and sends data through carrier aggregation technology at the same time in the same geographic location, and each cell at least include one (or a pair) carrier(s) which can be used to transmit data independently.
Specifically, the multiple aggregated cells can use the same PCI (Physical Layer cell ID), while the carrier frequency and CGI (Cell Global ID) of each cell are different. CGI also can be called ECGI, that is E-UTRAN (Evolved Universal Terrestrial Radio Access Network) cell Global ID. UE can receive and transmit data in multiple (or multiple pairs) carrier of multiple cell sets in which the carriers can be aggregated at the same time, so as to improve data transmission rate. To ensure UE can work in each aggregated carrier, the maximum bandwidth of each carrier can not exceed 20 MHz. The CA technology in LTE-A system is shown in FIG. 2, the base station of LTE-A have four carriers which can be aggregated, the base station can do data transmission in four carriers at the same time with the same UE, to improve the data transmit rate of user.
In LTE-A system, the channel quality of the carriers which can be aggregated needs to be estimated before and during serving process for UE. The base station do the carrier management, and decide whether the carrier which can be aggregated can be used to transmit data. For example, if channel quality of a carrier is better and meet the condition of CA, when a UE need to transmit lots of traffic, the base station can utilize this carrier by CA to provide data transmission service for the UE; if a UE is performing CA transmission, while the channel quality of one aggregated carrier of UE turns bad and does not satisfy the setting condition, then base station can deactivate or delete this carrier, do not use it provide service to UE, and can also activate another carrier which satisfy the setting condition and has better the channel quality, to provide service to UE.
Furthermore, in current LTE-A system, each cell only has one (or a pair) carrier which can work independently, and identified by a unique CGI. As shown in FIG. 3, wherein, carrier frequency of cell1 is f1, carrier frequency of cell2 is f2. These two carriers (corresponding to cell 1 and cell 2, respectively) are aggregated to provide service to a certain terminal. the channel quality of cell 1, cell 2 and cell 3 need to be estimated, so that the base station can do the carrier management to decide whether do carrier aggregation with carriers which can be aggregated to provide better transmission for terminal.
But to the carrier (or called “frequency”) (for example, cell4 and cell 5) which can not be aggregated with the working carrier (cell1 and 2), also need to do mobility measurement, so that the base station can perform mobility management (for example, handover or other management operation). Specifically, if the cell 1 and cell 2 of base station 1 have bad channel quality and can not provide service for terminal, while the cell4 and cell 5 of base station2 have better channel quality and can provide service for terminal, the network will switch the terminal from the cell 1 and cell 2 of base station 1 to the cell4 and cell 5 of base station2, that is, through (multicarrier) handover, CA transmission can continue, and the terminal can be provided with high-speed services all the time.
In the present technology, the evaluation of channel quality is base on that in LTE system. Base station sends measurement configuration information to UE through RRC (Radio Resource Control) signalling, UE implements measurement according to the content of the measurement configuration information (that is, estimate the channel quality, including intra-frequency measurements, inter-frequency measurement, inter-RAT measurements and other measurement process), and reports the measurement result to network.
As shown in FIG. 4, the RRC connection reconfiguration process which is used to configure measurement for network, comprising: network side E-UTRAN sends RRC connection reconfiguration message to UE; UE sends RRC connection reconfiguration complete message to E-UTRAN. Wherein, the RRC connection reconfiguration message include: measurement object, report configuration, measurement ID and other parameter.
Corresponding, measurement report has three kinds of trigger type, comprising: event triggered measurement report, periodical triggered measurement report and event triggered periodical measurement report. The said three kinds of trigger type can be distinguished according to combination of various parameters in reporting configuration. For example, when the trigger type in reporting configuration is “event” triggered, and the threshold value of the event and the time which need to be met to trigger a measurement report are also be configured, but if the interval of measurement or number of reports sent does not be configured, UE will report measurement results according to event triggered measurement report with number of reports sent equal to one.
Specifically, each measurement reporting message can only report measurement content corresponding to one measurement ID, that is, only the measurement quantity of UE serving cell and the cell which is corresponding to the frequency indicated by measurement object and meet the requirements of reporting configuration can be reported.
In conclusion, the present technology at least have the follow disadvantages: in multicarrier system, if UE want to perform measurement report for the aggregated component carriers of UE or for the measurement quantity of neighbor cells corresponding to the UE aggregated carriers, the frequency of each carrier or neighbor cell all need to use a measurement reporting message. When multiple UE aggregated component carriers or neighbor cells of multiple frequency need to be reported, it will need many messages to do it. Thus it will increases signalling cost. In addition, because the network side can not obtain the channel information of other component carriers of UE except for the carrier corresponding to the measurement report message, thus it will influence to the management of UE component carrier and handover judgment (mobility management) of UE in CA scenarios.